MPP on Solana
The Machine Payments Protocol (MPP) is an IETF draft standard co-authored by Stripe and Tempo for HTTP 402-based machine payments. Dexter brings MPP to Solana with managed settlement, gas sponsorship, and non-custodial session support.
Two Payment Modes
MPP on Dexter supports two settlement models. Both are live on Solana mainnet.
Charge (Per-Request)
Each API call settles individually. Dexter co-signs as fee payer, simulates, broadcasts, and confirms. Buyer needs zero SOL.
Sessions (Streaming)
Deposit once, pay with signed vouchers, settle at close. Two on-chain transactions regardless of request count.
When to Use Which
| Scenario | Mode | Why |
|---|---|---|
| Occasional API calls | Charge | Simple, no setup beyond a wallet |
| High-frequency requests | Sessions | 2 transactions vs. N transactions |
| Agent orchestration | Sessions | Continuous payment channels for long-running tasks |
| Content APIs, webhooks | Charge | One-off access pattern |
| Streaming data, model inference | Sessions | Cumulative billing with microsecond verification |
What Dexter Handles
Sellers install @dexterai/mpp and write payment logic. Dexter handles everything else:
- Solana RPC connections and failover
- Fee payer wallets funded with SOL
- Transaction simulation before broadcast
- Broadcast, confirmation, and retry logic
- Blockhash expiry and re-signing
- Security policy enforcement (program allowlists, compute unit caps)
- Session lifecycle management, voucher signing, balance monitoring
Integration Guides
Session Server
Accept streaming session payments. Voucher verification, challenge responses, metering.
Session Client
Open sessions, pay with vouchers, close and settle. Buyer onboarding with Swig wallets.
API Reference
All charge and session endpoints with request/response schemas.
MPP vs x402
When to use @dexterai/mpp vs @dexterai/x402. Protocol differences and overlap.